TA right? Well, an algorithm would take over your ship designs by striking a "strange but random" balance between weapons & defenses component % sliders. Whether the Engines, supports, sensors & others were left out by SD devs is an entirely different issue (or is it, really) but i fully expect them to fix or tweak this important feature in an update - eventually.

Otherwise, i (had) no choice but to leave it alone for the busy cleanup work necessary once hundreds of different designs started to fill out the available list.

You don't have much control over how the auto ship designer designs ships. You can tell it to focus on the use of specific weapons (like 50% laser, 50% missiles) and specific defense types (like 50% shields, 50% armor), but you can't specify the balance between guns and defense. You also can't tell it to use HP boosting modules, engines, sensors, life support, atlas modules (fleet modules), or fleet warp bubbles. The designer also doesn't modify designs for colony ships, constructors, trade ships, etc.

Overall its quite limited, but I find you can usually trust it to build decent combat ships. I don't often design my own ships now a days. Mind you, I usually have a significant technological edge. Its difficult to design bad ships if you are using technologies better than your opponent.

Also, the game will only use the default ship templates for the civ you are playing. You can't design an awesome looking ship template and then tell the game to start using it. Modders probably know a way around it though.

How about-its a just a fairly useless feature that even if it did work properly(which it does not), would at best be, of marginal utility. Once I mastered the art of making my own designs, and disabled the boxy looking stock designs, I found the game a lot more fun. The few times I tried to use the 'focus' button, all I learned was i was spending too much time focusing on something that didn't really do anything very useful.

So I stopped trying ages ago.

My 2cents? Ignore it-make your own ships that appear in a linear fashion-building on previous designs(your own). Its much more fun-and it works. My designs hold there own even against superior numbers because the game frankly, seldom maxes the tech trees. The few times the AI has, well, damn, there ships can be tough, but that seldom happens. Even with numerical superiority , even my med and L class fleets do very well most times. I never change my designs armor types even to match the AIs preferred weapons-there is seldom any need to.